UHPC预制管混凝土组合高墩收缩徐变分析

Analysis of Creep and Shrinkage of Concrete-filled UHPC Tube Composite High Piers

超高性能混凝土(UHPC)具有超高力学性能和超高的耐久性能,且蒸养过后具有无收缩、低徐变的特征,基于此提出UHPC预制管内浇普通混凝土形成UHPC-NC组合墩柱,应用于高墩桥梁中,以解决其因收缩徐变引起长期变形过大的问题。首先进行了NC、UHPC的收缩徐变试验,明确了材料的收缩徐变规律,同时采用ANSYS建立了相应的有限元模型,计算结果与试验值吻合良好,验证了建模方法的合理性。最后,以实际工程为原型建立了NC高墩和组合高墩的有限元模型,分析了两类墩柱的长期变形和内力重分布规律,结果表明:组合高墩相比NC高墩长期变形明显减小;UHPC管厚度越大,长期变形越小,内力重分布程度越大;当管壁厚度超过5 cm时,墩顶沉降减小40%以上,徐变系数减小50%以上。

Ultra-high performance concrete(UHPC)exhibits excellent mechanical properties and durability,and exhibits almost no posttreatment shrinkage and minimal creep after steam curing.Motivated by the creep and shrinkage behaviors of UHPC,an innovative NC-UHPC composite structure is proposed in this paper to solve the problem of excessive deformation of high piers caused by creep and shrinkage.This structure is formed by pouring nomal concrete in the precast UHPC tube.The creep and shrinkage characteristics of NC and UHPC are experimentally evaluated by the creep and shrinkage tests,and the tests are also simulated accurately by ANSYS,which proves the modeling method to be correct.The finite element models of NC high piers and NC-UHPC composite high piers are established based on an engineering example,and the long-term deformation and internal force redistribution of the two types of piers are analyzed.The results show that:compared with NC high pier,the long-term deformation of composite high pier is significantly reduced.The larger the thickness of UHPC tube is,the smaller the long-term deformation is,and the greater the degree of internal force redistribution is.When the thickness of UHPC tube is more than 5 cm,the settlement of pier top is reduced by more than 40%,and the creep coefficient of pier is reduced by more than 50%.